The invention relates to a medical instrument for irrigation and/or suction, with an instrument body in which at least one flow channel is present for the passage of a fluid, and with at least one shut-off member for alternately shutting off the at least one flow channel, and with an actuating member for actuating the shut-off member.
An instrument of this kind is known from the German utility model DE 200 11 409 U1.
Such a suction and/or irrigation instrument is used in surgery, in particular in minimally invasive surgery, in order to irrigate the operating site with irrigation fluid during a surgical intervention and/or to aspirate fluid, for example the introduced irrigation fluid, blood and tissue remnants from the operating site.
The aforementioned known instrument is suitable both for irrigation and for suction. Although the present invention is preferably described taking the example of an instrument for irrigation and suction, the present invention is not however restricted to this, and instead it also includes those instruments which can be used either only for irrigation or only for suction.
Likewise, the term “instrument body” within the meaning of the present invention is to be understood in its general sense and can include the shaft of such an instrument and/or the handgrip of such an instrument.
In accordance with its dual function, the known instrument for irrigation and suction has two flow channels in the instrument body, one flow channel representing the irrigation channel and the other flow channel representing the suction channel. The irrigation channel and the suction channel are separate from one another.
At the proximal end of the instrument, the known instrument has an attachment piece for attaching a suction tube and an attachment piece for attaching an irrigation tube. The suction tube and the irrigation tube are connected to a suction and irrigation source, a suitable underpressure being established on the suction tube and directed from the distal end to the proximal end of the instrument, and irrigation fluid being conveyed through the irrigation tube from proximal to distal. The suction underpressure and the irrigation fluid are preferably permanently present on the instrument after the suction and irrigation source has-been switched on.
In order to be able to interrupt the suction stream and/or the irrigation stream, the known instrument is provided with a shut-off member for alternately shutting off or free the respective flow channel, and the shut-off member can be actuated by the operator via an actuating member in the form of a slide. In the known instrument, the shut-off member has a movable plate connected to the slide, provided with recesses and arranged to slide on an immovable plate in the instrument body. The immovable plate is designed with openings which communicate with the at least one flow channel. By actuating the slide, the movable plate is displaced relative to the immovable plate, so that the recesses of the movable plate and the openings of the immovable plate move into or out of coincidence. In this way, the suction stream or the irrigation stream can be freed, or the suction channel and/or the irrigation channel can be shut off. The movable plate and the immovable plate lie directly on one another, their surfaces touching one another, both plates being made of a ceramic material in the area of their touching surfaces.
A disadvantage of this known construction is that ceramic plates of this kind are very expensive to produce. Moreover, when there are high suction or irrigation pressures, these kinds of ceramic plates lying on one another require high locking forces in order to achieve the necessary sealing action. These high locking forces in turn generate a high level of friction between the movable and the immovable plate, resulting in high operating forces upon actuation of the actuating member.
The object of the invention therefore is to develop an instrument of the type specified in the introduction in such a way that the aforementioned disadvantages are avoided, i.e. a good sealing action of the shut-off member is achieved, and yet the operating forces for actuating the shut-off member are kept as low as possible.